Authenticating a device in a communication network of an automation installation

Abstract

A method authenticates a device in a communication network of an automation installation, in which authentication information indicating the device is transmitted to an authentication server that admits or rejects the device in the communication network as a subscriber. To perform an authentication of the device in a communication network configured with redundancy, the communication network has a communication ring that, besides the device, has first and second neighbor devices. At the start of the authentication the device sends authentication requests containing the authentication information to the neighbor devices. The neighbor devices duplicate the authentication information and send it via the communication ring in both transmission directions to an authentication server which uses the authentication information to perform a respective check on the authenticity of the device and admits or rejects the device in the communication network as a subscriber as the result of the check.

The invention claimed is: 
     
       1. A method for authenticating a device in a communication network of an automation installation, which comprises the steps of:
 transmitting authentication information indicating the device to an authentication server and the authentication server taking the authentication information as a basis for admitting or rejecting the device in the communication network as a subscriber, the communication network having a communication ring that, besides the device, having at least one first neighbor device and a second neighbor device, the device being connected to the at least one first neighbor device via a first communication port and to the second neighbor device via a second communication port for redundant data transmission, the transmitting step includes the substeps of:
 using, at a start of authentication the device, the first communication port to send a first authentication request containing the authentication information to the at least one first neighbor device and using the second communication port to send a second authentication request containing the authentication information to the second neighbor device; 
 duplicating the authentication information respectively received, via the at least one first neighbor device and the second neighbor device, and sending the authentication information via the communication ring in both transmission directions to the authentication server connected to the communication ring; and 
 the authentication server using the authentication information respectively received to perform a respective check on an authenticity of the device and admitting or rejecting the device in the communication network as the subscriber as a result of the respective check. 
 
 
     
     
       2. The method according to  claim 1 , which further comprises configuring the communication network for the redundant data transmission in accordance with standard International Electrotechnical Commission 62439-3 high-availability seamless redundancy protocol. 
     
     
       3. The method according to  claim 1 , which further comprises performing a reciprocal authentication via the device and the first and second neighbor devices. 
     
     
       4. The method according to  claim 1 , which further comprises:
 checking the authenticity of the device by comparing the authentication information received with reference authentication information and/or checking a certificate contained in the authentication information for whether it is trusted; and 
 admitting the device in the communication network in an event of a match. 
 
     
     
       5. The method according to  claim 4 , which further comprises sending a respective authentication response to the at least one first neighbor device and the second neighbor device as a reaction to a check, the respective authentication response indicates whether or not a respective neighbor device may admit the device in the communication network for a purpose of communication. 
     
     
       6. The method according to  claim 1 , which further comprises connecting the authentication server to the communication ring via a redundancy ballast, the redundancy ballast being connected to the communication ring via two communication ports and to the authentication server via a further communication port. 
     
     
       7. The method according to  claim 6 , which further comprises connecting the authentication server to the communication ring via two communication ports. 
     
     
       8. The method according to  claim 1 , wherein if the communication ring is interrupted then the two devices adjoining a location of an interruption each perform a fresh authentication after a connection is restored. 
     
     
       9. The method according to  claim 1 , wherein the device has a first authentication apparatus, which is connected to the first communication port via a first port access control unit, and a second authentication apparatus, which is connected to the second communication port via a second port access control unit, a respective one of the first and second authentication apparatuses generates a respective authentication request and sends the respective authentication request via the respective first or second communication port. 
     
     
       10. The method according to  claim 9 , wherein the first port access control unit and the second port access control unit are connected to a redundancy unit of the device and are configured so as, during the authentication of the device, to forward exclusively messages that are used for authenticating the device between the redundancy unit and the first and second communication ports and to block a forwarding of other messages, and to forward the other messages between the redundancy unit and the first and second communication ports only after successful authentication of the device. 
     
     
       11. The method according to  claim 10 , wherein after successful authentication of the device the redundancy unit duplicates telegrams to be sent by the device and sends them via both of the first and second communication ports and inspects telegrams received from the device for whether an identical telegram has already been received, and forwards the telegram received to an application layer of the device or discards the telegram on a basis of the respective check. 
     
     
       12. The method according to  claim 1 , which further comprises connecting the device to a redundancy ballast via a single communication port, the device generating an authentication request and sends the authentication request via the single communication port, and the redundancy ballast sends the authentication information of the device to the at least one first neighbor device via the first communication port and sends the authentication information to the second neighbor device via the second communication port. 
     
     
       13. A communication network of an automation installation, comprising:
 an authentication server; 
 a device to be authenticated and having a first communication port and a second communication port; 
 a communication ring having, besides said device, at least one first neighbor device and a second neighbor device, said device being connected to said at least one first neighbor device via said first communication port and to said second neighbor device via said second communication port for redundant data transmission; 
 the communication network configured to authenticate said device by performing the steps of:
 transmitting authentication information indicating said device to said authentication sever and said authentication server taking the authentication information as a basis for admitting or rejecting said device in the communication network as a subscriber, the transmitting step includes the substeps of:
 using, at a start of authentication said device, said first communication port to send a first authentication request containing the authentication information to said at least one first neighbor device and using said second communication port to send a second authentication request containing the authentication information to said second neighbor device; 
 duplicating the authentication information respectively received, via said at least one first neighbor device and said second neighbor device, and sending the authentication information via said communication ring in both transmission directions to said authentication server connected to said communication ring; and 
 said authentication server using the authentication information respectively received to perform a respective check on an authenticity of said device and admitting or rejecting said device in the communication network as said subscriber as a result of the respective check.